1. Field of the Disclosure
This disclosure generally relates to an interactive system and, more particularly, to an optical touch system.
2. Description of the Related Art
An optical touch system may belong to a passive touch system. Different from active touch systems, a pointer configured to control the passive touch system does not consume power such that a user may use any object to be served as the pointer, such as a finger of the user. In this manner, the user does not need to carry an additional pointer with him or her such that the operational convenience is significantly increased. In an optical touch system, how to recognize the two-dimensional position of a contact point is an important topic.
For example, U.S. Pat. No. 6,803,906, entitled “Passive touch system and method of detecting user input”, discloses a passive touch system 9 as shown in FIG. 1. The touch system 9 includes a touch surface 90, four two-dimensional image sensors 91 and a processor 92. The two-dimensional image sensors 91 are configured to acquire two-dimensional images looking across the touch surface 90, and the processor 92 calculates the coordinate of a pointer with respect to the touch surface 90 according to the two-dimensional images.
In the passive touch system 9, the images acquired by the two-dimensional image sensors 91 contain two-dimensional information such that the processor 92 has to process a large amount of data. Therefore, to avoid processing too much useless information by the processor 92, the passive touch system 9 selects a subset of pixels in the two-dimensional images acquired by the two-dimensional image sensors 91 in the alignment routine so as to decrease the amount of data. During normal operation, only the image data of the selected subset of pixels is calculated and other image data without being selected is ignored. However, due to this operation method, said passive touch system 9 has at least the following problems:
(1) An additional step to select a subset of pixels has to be added in the alignment routine; (2) the selected subset of pixels may not be the best image block, e.g. when the touch surface 90 is bent, it may not be able to select a proper subset of pixels such that an error in post-processing may be induced; (3) the selected subset of pixels is a rectangle and a large amount of useless information is still contained therein such that the amount of data transmission and the calculation in post-processing can not be effectively decreased; and (4) the image sensor having a large pixel array has to be employed in order to clearly extract the pointer image such that the image sensors 91 require a larger installation space and are not suitable for electronic products having a small touch surface; and if a smaller pixel array is used, it may not be able to clearly extract the pointer image to degrade the ability of recognizing the touch status.
According, the present disclosure provides an optical touch system that converts the two-dimensional information into the one-dimensional feature at first and then positions the pointer. Even though the image sensor having a small pixel array is employed, the validity of the image data is improved through the dimension conversion such that the amount of data transmission is reduced to be suitable for electronic products having a small size.